Hi I just bought my first truck 2000 Silverado 1500 z71 5.3L 180k miles, what is right weight for front/rear/transfer case oil to use ? and 1 question, when I look at rear diff, I see at the bottem it have a plug, but I cant find the other plug ?

You can cehck the owners manual and it will tell you exactly what you need to use for all the components as well as the amount you will need. If you have lost or do not have an owners manual you can go to the home page of this website and there is a list of the owners manuals down towards the bottom. You can click on the one for your truck and open it up. You truck has the transfer case that takes the special GM only lube.

75W-90 synthetic front and rear. GM revised the front gear lube use to use 75W-90 synthetic, see below. All you need is a GL5 rated oil, the GM spec is for a GL5 gear lube. There not going to tell you that or you will not buy it from them.

•API Category GL-5 designates the type of service characteristic of gears, particularly hypoids in automotive axles under high-speed and/or low-speed, high-torque conditions. Lubricants qualified under U.S. Military specification MIL-L-2105D (formerly MIL-L-2015C), MIL-PRF-2105E and SAE J2360 satisfy the requirements of the API GL-5 service designation.

What ever you do DO NOT use a Limited Slip Additive in a locking rear differential. The use of any additive in locking rear axles (G80) is not recommended. Rear axle additives are designed for use in limited slip differentials which are normally installed in cars. All light duty trucks equipped with RPO G80 make use of a locking differential and the use of additives will delay the engagement of the locking mechanism and may decrease axle life.

so you mean I can use any 75w90 synthetic, for example mobil 1 75w90 front and rear RIGHT ? and when fill the front diff and rear diff, fill until fluid come out the fill hole right ? cause the tag on the rear diff say I have to fill below the fill hole, i have no idea how to measure that. I alway fill until it come out fill hole then stop, that ok right ?

Transmission and drivetrain related components. Discuss automatic and manual trans repairs and performance or talk about driveshafts or rear-ends and differentials. Diagnostics of 4-speed, 5-speed, or even 6-speed transmissions.